Ohm’s Law Pie Chart is a great tool to make quick electric calculations (see a picture). It includes twelve patterns which address any mode of famous electric law. Instead of searching for reference to one of these particular formulas somewhere else, here you cover all the calculation approaches to Ohm’s principal at this single easy-to-use chart. The chart is seeable and understandable. It is fun to use even for kids, and it’s tasty – remember, it’s a “pie”!

How to use Ohm’s Law Pie Chart

The Ohm’s Law Chart is divided into four main quarters. We’ve got twelve pie slices around. In the inner circle we have four variables. These variables are what we don’t know, what we are trying to find:

“P” – for Power

“E” – for Electromotive Force

“R” – for Resistance

“I” – for Current

The slices of the pie represent given/known data in each case.

Each of the variables we are trying to find has three pie slices – three equations. Now, depending on what two numbers (two types of data) we know – we choose the appropriate equation which would fit our interest and resolve the question.

For example, you need to calculate Power using Ohm’s law formulas and you know, let’s say Electromotive Force value and a Current value. Power is “P” so you choose left upper (red) quarter of the chart to begin with. Now, Electromotive Force is “E” and a Current is “I”. Take a look at the slices in quarter “P” and find out which one of the three corresponding pie slices has BOTH: E and I. In this case it is the slice on the left hand side which says:

“E x I” which means

P = E x I (“P” is equal “E” multiplied by “I”)

So just multiply the two numbers you already know and get the result. That’s it!

You could calculate a value of any variable in the chart using this principal of finding the appropriate formula.

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Theoretical excursion

Ohm’s law states that the current through an electric transmitter between two spots is straightly proportional to the electromotive force across the two points. Introducing the unchanging factor of proportionality – the resistance, the logic arrives at the mathematical equation that describes this relationship where the current (“I”) through the conductor in units of amperes, the electromotive force (“E”) measured across the conductor in units of volts, and the resistance (“R”) of the conductor in units of ohms all bound in a certain relation of proportionality: E = I x R. More specifically, this rule states that the impedance in this relation is constant, independent of the current.

The Law was named after the German physicist Georg Ohm, who, in a monograph published in 1827, reported measurements of applied voltage and current through regular electrical circuits containing diverse lengths of wire. He presented a slightly more complex equation than the one we all know today to explain the main discovery which was result of series of experiments. The widely known equation E = I x R is the modern form of Ohm’s principal.

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